Zeolites are crystalline aluminosilicate compositions which are microporous and which are formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. Synthetic zeolites are prepared via hydrothermal synthesis employing suitable sources of Si, Al, as well as structure directing agents such as alkali metals, alkaline earth metals, amines, or organoammonium cations. The structure directing agents reside in the pores of the zeolite and are largely responsible for the particular structure that is ultimately formed. These species balance the framework charge associated with aluminum and can also serve as space fillers. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure. Zeolites can be used as catalysts for hydrocarbon conversions, which can take place on outside surfaces as well as on internal surfaces within the pore.
U.S. Pat. No. 4,209,498 discloses an aluminosilicate zeolite designated as FU-1 along with a method of preparing the zeolite and uses for the zeolite. The '498 patent states that FU-1 is prepared using a “methylated quaternary ammonium” cation along with an alkali metal. It is further stated by the patentees that the FU-1 zeolite has a Si/Al ratio greater than 2.5 and can be used for xylene isomerization.
An all-silica version of FU-1 was reported in U.S. Pat. No. 4,689,207. The synthesis employs the layered silicate magadiite and the Na/ethyltrimethylammonium (ETMA) template system. The solid product was identified as containing 20% FU-1 by x-ray analysis.
A number of applications have been identified for the FU-1 zeolite. Besides the xylene isomerization mentioned above and disclosed in GB1563346, the conversion of alkylbenzenes, such as xylenes and ethylbenzene is described in GB2052554A, GB2006818, GB2042490, and GB2006262. U.S. Pat. No. 4,172,856 describes the use of FU-1 to make olefins from methanol or dimethylether as preferred feedstocks while U.S. Pat. Nos. 4,191,709, 4,205,012, and GB2013660A describe the synthesis of amines from alcohols using a FU-1 based catalyst. Finally, FU-1 based catalysts have been described for the cracking of heavy fractions to naphtha-type products in U.S. Pat. No. 4,197,186.
Applicants have prepared a family of zeolites, designated UZM-15, which have an x-ray diffraction pattern similar to but distinct from that of FU-1 and is different in other characteristics. One difference is that the as-synthesized UZM-15 contains at least one quaternary organoammonium cation template where at least one of the organic groups has at least two carbon atoms. Preferred templates are selected from ETMA, DEDMA, TMBA, PEDMA and optionally alkali metals, alkaline earth metals and/or other organoammonium cations. The Si/Al ratio of the UZM-15 zeolites ranges from about 7 to about 50 and the aluminum can be replaced by other metals such as gallium or iron.
Applicants have also prepared dealuminated versions of UZM-15 designated UZM-15HS. The UZM-15HS materials have different properties from the starting UZM-15, including different ion-exchange capacities, acidity, and porosity.